Compacting devices are necessary for use in conjunction with refilling excavated sites. For example, when a trench is dug for the purpose of laying an underground pipeline and after the pipeline has been installed in the trench, it is necessary to fill the trench with the excavated soil. It is important that the surface of the ground be returned its original grade so that drainage patterns are not altered because of the excavation activity. This requires that the fill material placed in the trench be compacted to its original density in order to avoid settling over a period of time after the excavation crews and machinery have departed the site.
Compacting fill in trenches requires a great deal of pressure, and the pressure is conveniently applied by the excavating equipment of the type including a hydraulically-actuated articulated arm extending from a heavy chassis and engine vehicle. Thus, it is convenient to provide a compaction unit which mounts to the end of the articulated arm. Of course, it is desirable that a compaction unit operate efficiently in terms of the amount of time required to compact a given volume, particularly inasmuch as the cost and operation of the heavy excavating equipment is high. The compaction units are used in highly adverse conditions, being subjected to almost constant abrasion and impact. It is desirable that a compaction unit have longevity and require low maintenance, and preferably that basic maintenance be performable in the field. On occasion it is necessary to cut through pavement as a part of the excavating process, which is usually accomplished by either individual workmen with pneumatic hammers or by specialized cutting equipment. A compaction unit adaptable to this purpose would also be beneficial.